A persistent problem common to virtually all petroleum products and petroleum-related products is their tendency to undergo oxidative degradation. Oxidation may occur even under the relatively mild conditions attending storage and transport, and is appreciably accelerated when operating conditions are conducive to oxidative processes, for example the elevated temperatures experienced by lubricating oils. Such oxidative processes not only cause chemical degradation of the petroleum or petroleum-related product, but may also cause appreciable changes in desirable physical properties, such as viscosity, which lead to a deterioration in performance of the product. Additionally, the oxidative products themselves may attack materials in contact with petroleum and petroleum-related products, such as metals in contact with transmission or lubricating oils, thereby inducing inefficient performance and, in some cases, even structural failure.
It has now been found that acetoacetanilides and other beta-ketoanilides are effective antioxidants in the aforementioned products. In some cases these materials display antioxidant properties exceeding those of available antioxidants, thereby permitting their effective use at relatively lower levels. The antioxidants described herein possess the further advantage that structural changes within broad, but nonetheless well defined, limits are possible, thereby permitting optimization of the antioxidant for a particular product in a specified use.